This invention relates to pipe bending machines, and more particularly to a cam assembly for adjusting the distance between opposed pipe bending dies.
Pipe bending machines include die halves or die blocks that have cavities or grooves for receiving and contacting the pipe or tubing during the bending operation (hereinafter collectively referred to as “pipe”). Typically, a pipe bending machine comprises at least two dies, a pressure die and a forming die. The pressure die applies bending pressure to the pipe around the curvature of the forming die. The forming die, pressure die, or both rotate relative to the other to achieve the required bending pressure to bend the pipe.
Typically pipe bending machines are adapted to bend pipes of various diameters. As different sized pipes are fed into the machine between the pressure die and the forming die, it is necessary to adjust the distance between the two dies to avoid abnormalities in the bent pipe. For example, if the pressure die is too close to the forming die before the bending begins, the pressure die may not be able to be rotated fully into position for bending, rather, it may interfere with the forming die during bending which may create excessive drawing of the pipe being bent as well as galling the pipe surface. If the pressure die is too far from the forming die before the bending begins the pipe will not fully seat into the pressure die groove causing wrinkling on the inside of the bend and flattening of the outside of the bend due to lack of drawing and shaping by the pressure die.
Traditionally the distance between the pressure die and forming die has been adjusted by changing the position of the pressure die on the bending arm. Bending arms typically have a plurality of openings adapted to receive bolts for securing the pressure die mounting assembly thereto. The pressure die can be mounted at various positions along the bending arm by securing the die mounting assembly into the openings. A similar concept is disclosed in U.S. Pat. No. 3,987,656 wherein aligned bores allow a motor to be secured in alternate positions along the length of the frame to permit the bending of pipes having various diameters.
The problem with these die adjustment means is that the openings in the bending machine's arm are a predetermined distance apart from each other, usually one inch. The openings do not allow for a continuous range of adjustment, which is problematic since pipe diameters and bend radii can vary infinitely. For example, a pipe may have a diameter that requires the dies to be set at a distance in-between the one inch settings on the machine's arm. The traditional adjustments can have adverse effects on the pipe being bent, as described above.
Therefore, there is a need for a pressure die mounting assembly which allows for an infinite adjustment of the position of the pressure die relative to the forming die on a pipe bending machine.